As it is you could save some code duplication by doing:

    var controlBarChildren = {
          'playToggle': {},
          'currentTimeDisplay': {},
          'timeDivider': {},
          'durationDisplay': {},
          'remainingTimeDisplay': {},
          'progressControl': {},
          'fullscreenToggle': {}
        };

    if (!vjs.IS_IOS) {
      controlBarChildren['volumeControl'] = {};
      controlBarChildren['muteToggle'] = {};
    }

    vjs.ControlBar.prototype.options_ = {
      loadEvent: 'play',
      children: controlBarChildren
    };

(there's already an check for iOS you could use in lib.js.)